The present invention relates to a boat lift apparatus for raising and lowering a boat at a seawall.
It is common to dock boats at piers that project into the water from a shoreline. Raising and lowering the boat can be accomplished by a vertical hoist mechanism which moves the boat vertically, e.g., by raising and lowering a boat-carrying cradle in a vertical direction as disclosed in U.S. Pat. Nos. 4,900,187 and 5,803,003. Such vertical hoists are suitable for use in cases where the water beneath the cradle is deeper than the boat displacement. However, in many situations the water is very shallow at a location beneath the cradle and becomes progressively deeper away from the lifting mechanism. Such a condition may occur along a seawall that follows the shoreline. Vertical hoists are not useful under those conditions.
In many places, local ordinances prohibit the construction of docks along the seawall, thereby making it difficult to raise and lower a boat due to the need to displace the boat not only downwardly but also outwardly to the deeper water when lowering the boat. Conversely, the boat must be not only be moved upwardly, but inwardly toward the seawall when raising the boat. Moreover, it becomes more difficult to enter the boat once it has been lowered, since it has been moved away from the seawall.
Various boat lifting apparatus have been proposed which result in the boat being moved toward a seawall when raised, and moved away from the seawall when lowered, e.g., see U.S. Pat. Nos. 4,641,996 and 3,675,258. U.S. Pat. No. 4,641,996 discloses rails inclined downwardly and outwardly from a seawall, and a boat cradle slidable along the rails. A shortcoming of such an apparatus involves the fact that the rails are permanent installations, wherein lower ends of the rails are anchored in pilings. Such permanent submerged installations are not only expensive to install, but may be prohibited in many localities.
In U.S. Pat. No. 3,675,258 a boat hoist is disclosed in which a boat supporting platform is connected to an outer end of a scissor apparatus, an inner end of which is connected to a vertical side of a seawall. When the scissor apparatus is extended, its outer end is in a lowered state to enable the platform to load (or unload) a boat. A cable mechanism is connected to the scissor mechanism for collapsing the scissor mechanism, whereby the platform is brought toward the seawall while simultaneously being raised. A shortcoming exhibited by this boat hoist is that since the inner end of the scissor apparatus is mounted on a vertical side of the seawall, a great moment is applied to the mounting when the scissor apparatus is in a collapsed boat-storing state. Thus, exceptional measures would have to be taken to strengthen this mount. Furthermore, when a boat approaches the hoist from the water, it is impossible for a boat occupant to leave the boat and directly enter the seawall to activate the hoist. Likewise, once a user activates the hoist to cause a raised boat to be lowered into the water, it is impossible for the user to directly enter the boat from the seawall. Accordingly, this type of hoist is of limited usefulness.
Therefore, it would be desirable to provide a boat lift adapted to move a boat not only up-and-down, but also away from a seawall when lowering the boat and toward the seawall when raising the boat. Such a boat lift should not involve any permanent submerged structures and should facilitate access to and from the boat when the boat is in a floating (launched) state. Also, any moments applied to an anchoring structure of the boat lift should be minimized when the boat is held in a raised state.
The present invention relates to a boat lift which comprises a base that is anchored adjacent to a shoreline of a body of water. A frame structure is provided for raising a boat from the water and lowering a boat into the water. The frame structure includes a swinging frame and a boat-supporting frame. The swinging frame has inner and outer ends. The inner end is swingably attached to the base by a first swinging coupling. The boat-supporting frame has proximate and remote ends. The proximate end is swingably attached to the swinging frame adjacent the outer end thereof. A section of the boat-supporting frame disposed adjacent the remote end thereof defines a boat-supporting structure arranged to support an underside of a boat. The boat lift further includes an actuator operably connected to the frame structure for causing the swinging frame to swing relative to the base about the first swinging coupling, wherein the boat-supporting frame moves upwardly and inwardly toward the base to a boat-storage position when the swinging frame swings in one direction. The boat-supporting frame moves downwardly and outwardly away from the base to a boat-launch position when the swinging frame swings in an opposite direction. The boat supporting structure remains in a substantially horizontal state during up-and-down movement of the boat supporting frame. The frame structure forms a walkway arranged for providing users with access between the shoreline and the boat-supporting structure when the boat-supporting frame is in its boat-launch position.
In another aspect of the invention, a boat lift comprises a rigid support structure anchored on land adjacent to a body of water. The support structure includes a horizontal portion disposed over the land. A base is mounted on the horizontal portion of the support structure. A frame structure is provided for moving a boat between raised and lowered positions. The frame structure includes a swinging frame, a boat supporting frame, and a stabilizing structure. The swinging frame includes a pair of parallel, spaced apart base arms. Each base arm includes an inner end mounted to the base by a first swinging coupling, enabling an outer end of each base arm to swing upwardly and inwardly, or downwardly and outwardly, depending upon a direction of swinging movement of a swinging frame. The boat-supporting frame includes a pair of parallel, space apart support arms. Each support arm includes a proximate end mounting directly to an outer end of a respective base arm by a second swinging coupling. The support arms include respective remote portions arranged for supporting an underside of a boat. The stabilizing structure is connected to the boat-supporting frame for maintaining the remote portions in a horizontal state during up-and-down movement of the boat-supporting frame. An actuator is operably connected to the frame structure for causing the swinging frame to swing relative to the base about the first swinging coupling. The boat-supporting frame thus moves upwardly and inwardly toward the base to a boat-storage position when the swinging frame swings in one direction. The boat-supporting frame moves downwardly and outwardly to a boat-launch position when the swinging frame swings in an opposite direction. The first and second swinging couplings are disposed in vertically overlying relationship to the horizontal portion of the support structure when the boat-supporting frame is in its boat-storage position.
In a further aspect of the invention, boat lift apparatus is mounted on a horizontal platform disposed on land. A front portion of the platform underlies a rear portion of a top ap of a seawall.